Chapter 9 - Sleeping & Waking Flashcards
endogenous circananual rhythm
self-generated rhythm that lasts about a year
endogenous circadian rhythm
self-generated rhythm that lasts abhout a day
name several circaidan rhythms
eating, drinking, urination, secretion of hormones, sensitivity to drugs, temperature, mood and more.
what evidence indicates that humans have an internal biological clock?
people who have lived in an environment with a light/dark schedule much different from 24 hours fail to follow that schedule and instead become wakeful and sleepy on about a 24hr basis.
can circadian rhythms persist without light?
yes.
what can reset circadian rhythms?
light is critical for resetting circadian rhythms.
zeitgeber
the stimulus that resets the circadian rhythm. (meaning “time-giver”)
what other zeitgebers are there?
tide (for marine animals), exercise, arousal, meals, and temperature.
how do the blind set circadian rhythms without light?
some use noise, temperature, meals and activity. others produce circadian rhythms a little longer than 24 horus.
why do people at the eastern edge of germany awaken earlier than those at the western edge on their weekends and holidays?
the sun rises about 30 min earlier at the eastern edge. the sun seems to control the wake/sleep schedules een when people follow the same clock time.
jet lag
disruption of circadian rhythms due to crossing time zones
symptoms of jet lag
sleepiness in the day, sleeplessness at night, depression and impaired concentration
phase-delay
the delay of circadian rhythms by traveling west. we stay awake later at night then wake late the next morning already partly adjusted to the new schedule
phase-advance
the advance of circadian rhythms by traveling east. we go to sleep earlier and wake earlier. it is harder to do both.
how does jet lag and stress affect the brain?
jet lag increases stress, stress increases cortisol. prolonged elevations of cortisol damage the hippocampus (important for memory)
suprachiasmatic nucleus (SCN)
located just above the optic chiasm. provides main control of circadian rhythms for sleep and temperature.
what does damage to the suprachiasmetic nucleus (SCN) cause
it causes the body’s rhythms to become erratic
what evidence strongly idicates that the SCN produces the circadian rhythm itself?
SCN cells produce a circadian rhythm even when isolated from the rest of the body. also, when transplanted, the recipient has the rhythm of the new SCN.
retinohypothalamic path
small branch of optic nerve which extends from retina to the SCN. axons alter SCN’s settings.
melanopsin
special retinal ganglion cells that make up the retinohypothalamic path. respond directly to light. help reset the SCN
PER and TIM
Period & Time. genes which promote sleep and inactivity based on feedback from several sets of neurons.
what could a mutation in PER cause?
a circadian rhythm shorter than 24 hours. sleepy in the evening, waking up early. also may suffer from depression
how do the proteins TIM and PER relate to sleepiness in the drosophilia fly?
the proteins remain low during most of the day, increasing in the evening promoting sleep. they also inhibit the genes that produce them so their level declines toward morning (promoting wakefulness)
pineal gland
an endocrine gland posterior to the thalamus. releases melatonin (mostly at night)
melatonin
influences circadian and circannual rhythms
release of melatonin causes…
sleepiness
melatonin pill
can phase advance clock if taken in afternoon, can phase-delay if taken in the morning.
vegetative state
alternating between sleep and moderate arousal (no awareness of surroundings)
minimally conscious state
occasional periods of purposeful actions, limited speech comprehension
brain death
condition with no sign of brain activity, no response to stimulus
polysomnograph
combination of eeg and eye-movement records
alpha waves
characteristic of relaxation, to all wakefulness
sleep spindle
result of interactions between cells in thalamus and cortex. seen in stage 2
k-complex
sharp wave associated with temporary inhibition of neural firing. seen in stage 2
slow wave sleep (sws)
stages 3 and 4 together
what do long, slow waves on an EEG indicate?
low level of activity with much synchrony of response among neurons.
paradoxical sleep
high brain activity with relaxed muscles during sleep (used to describe REM sleep in non-humans)
rapid eye movement (REM)
high brain activity with relaxed muscles during sleep, accompanied by periods of eye movement.
non-REM (NREM) sleep
stages other than REM
locus coeruleus
small structure in pons, which emits bursts of impulses in response to meaningful events. release norepinephrine throughout cortex. strengthens storage of recent memories & increases wakefulness
pontomesencephalon
part of reticular formation. maintains arousal during wakefulness/increases during challenging or new tasks. releases acetylcholine & glutamate which excite cells in hypothalamus, thalamus & basal forebrain
reticular formation
structure that extends from medulla into forebrain.
orexin
peptite neurotransmitter that stimulate neurons responsible for wakefulness.
is orexin necessary for waking up or staying awake?
it is necessary for staying awake.
lack of orexin can cause…?
inability to sustain activities, and drowsiness.
PGO waves
waes that move from pons to lateral geniculate to occipital cortex. synchronized with eye movement in REM.
acetylcholine
important for wakefulness and REM sleep
serotonin and norepinephrine
interrupt REM sleep
insomnia
inadequate sleep
sleep apnea
impaired ability to breathe while sleeping. may wake up gasping but no remember. lack of sleep causes deficiencies of cognition
causes of sleep apnea
genetics, hormones, old age, obesity in middle aged men
narcolepsy
condition characterized by frequent periods of sleepiness during the day
what causes narcolepsy?
we’re not sure. it runs in families, but there is no gene for narcolepsy.
what neurotransmitter do people with narcolepsy lack?
orexin.
treatments for narcolepsy?
stimulant drugs such as Ritalin, which enhance dopamine and norepinephrine activity.
periodic limb movement disorder
repeated involuntary movement of legs and sometimes rms. different from the occasional kick, especially when falling asleep.
REM behavior disorder
people move around vigorously during REM periods. may be acting out dreams. may attack, punch or kick
night terrors
intense anxiety from which person wakes screaming. more severe than nightmare. occur during NREM and more common in children
function of hibernation
to conserve energy while food is scarce
activation-synthesis hypothesis
brains effort to make sense of sparce and distorted information. emphasis on the pons.
clinico-natomical hypothesis
theory of dreams that stimuli is generated within the brain and combined with recent memories and any other information coming in from the senses.
